Air conditioning process

ABSTRACT

A process for efficiently conditioning air for beneficial use by sequentially cooling dry air in three distinct steps, e.g., precooling the air out of the presence of moisture, adiabatically cooling the air in the presence of moisture, and refrigerating the air to finally cool the air and coincidentally condense excess moisture.

United States Patent 1191 Brown 1 11 3,812,685 1 1 May 28,1974

[5 AIR CONDITIONING PROCESS 1,863,577 6 1932 1,863,578 6/1932 Morse55/35 [761 Invent Ted Bmwn, 12,12 Prmcem" 1,909,823 5/1933 FOIICSI 62/ 4-1 Salt Lake Utah 84105 2,114,737 4/1933 Smith 62/94 2,355,828 8/1944Taylor 62/79 [22] May 1973 2,378,964 6/1945 Williams 72/182 [21] Appl.No 359,368 2,811,223 10/1957 Newton 62/92 3,041,842 7/1962 Heinecke62/95 Related Application D818 3,153,914 10 1964 Meckler 62 271 [63]Continuation-impart of Ser. No, 172,968, Aug. 19, v

1971' aband9ned- Primary ExaminerWi11iam J. Wye [52] U S Cl 62,93 62,27162ml Attorney, Agent, or Firm-11. Ross Workman 62/92 51 1111. C1. F251117/06 [57] 1581 Field 61 Search 62/271, 91, 92, 93, 94, A Process forefficlently qondltwnmg 5 for beneficial 2 95 use by sequennally coolmgdry alr mthree distmet steps, e.g., pre-cooling the air out of thepresence of 5 References Cited moist re, adiahatica1ly coeling theair in'the presence UNITED STATES PATENTS o1 molsture, 21nd refrlgeratmg thean to finelly cool the 1 749 763 3 1930 P16151161 .L 62 92 andcomcldemauy condense excess molsture' 1,863,576 6/1932 Morse 62/271 2Claims, 3 Drawing Figures WARM AIR (dry) WATER EVAPORATING EQL cow VERYcow AIR 76 f v WASHER 78 7 6g 6 1 COMPRESSOR COOL comaemsrza 4 1 AIRCONDITIONING PROCESS This invention is a continuation-in-part of mycopending application Ser. No. 172,968, filed Aug. 19, l97l, nowabandoned.

BACKGROUND ing systems are employed to produceconsistently cold air.This is particularly true where high temperatures are accompanied byrelatively high humidity levels. Socalled swamp cooler" type airconditioning systems become of almost negligible value when both thetemperature and humidity of ambient air are high.

Because of the great difficulty with which air is reduced to a very lowtemperature in hot summer months, most air conditioning systems havebeen engi-, neered so as to recirculate and recool the conditioned airinstead of continuously cooling fresh air. This procedure has been foundnecessary to keep the size and attendant costs of air conditioningsystems from becoming prohibitive. Until this present invention, aneconomical and efficient way of substantially reducing the temperatureof air or other gas for cooling purposes year-round withoutrefrigeration has not been known.

It is also well-known to condition air by successive cooling,humidifying, drying and recooling steps which are inefficient,complicated and expensive. See, for example. U. S. Pat. No. 1,863,578.

BRIEF SUMMARY AND OBJECTS OF THE INVENTION The present invention relatesto conditioning fresh air by sequentially (l) pre-cooling dry air out ofthe presence of moisture, (2) adiabatically cooling the air, and (3)refrigerating to finally cool the air and coincidentally condense excessmoisture. Surprising efficiency and cooling results from this processusing a total fresh air system and treatment of the air in quantitiesbetween 400 and 600 cubic feet per minute per ton of net sensiblein-space cooling.

It is, therefore. a primary object to efficiently provide air havingcontrolled temperature and humidity for air conditioning.

It is another important object to provide a process for effectingsensible cooling using a total fresh air system.

These and other objects of the present invention will become more fullyapparent from the following description and appended claims taken inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1, 2 and 3 are schematic flowdiagrams illustrating fluid circuits and apparatus for reducing airtemperature according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS General Heat exchangeprocesses such as used in air conditioning systems have always beenrequired to have increased capacity in order to adequately cool air whenthe temperature and/or the humidity of external air climbs as in summermonths and on hot days.

While it is relatively easy and comparatively inexpensive to remove heatfrom gases when the temperature of the gas is high, the difficulty withwhich heat is removed increases at an astonishing rate when thetemperature of the gas is already low. Thus, generally speaking, it ismuch easier and less expensive to make hot air cool than to make coolair cold using prior art techniques. Historically, the approach used tomake cool air cold was to increase the size and capacity of coolingsystems.

The present invention includes treating dry warm air out of the presenceof moisture to reduce its dew point.

Air most efficiently used with the illustrated embodiments has a dewpoint of not more than 57 which is low compared to the dry bulbtemperature of the warm air. This treatment can be performed bypre-cooling in a conventional heat exchanger.

According to the present invention, the temperature of the pre-cooledgas is then adiabatically reduced so that the gas is cold. Adiaba-ticprocesses are defined as those processes carried out insuch a mannerthat heat is not exchanged between the system and its surroundings.Thus, the adiabatic cooling step does not require an energy input toreduce the temperature. When the gas is adiabatically cooled accordingto the present invention, heat is not actually removed from the coolingsystem but is reduced psychrometrically. I If a stream of gas isintimately mixed with a quantity of recirculating liquid at a giventemperature in an adiabatic system, the temperature of the gas will dropand its humidity will increase. Furthermore, the temperature of therecirculating liquid will approach the wet bulb temperature of the gas.The low temperature gas which has been cooled adiabatically is subjectedto refrigeration which both further cools the air and coincidentiallycondenses excess moisture. 1

When percent fresh (unrecirculated) air is used for cooling, airquantities treated according to the pre ferred embodiments of theinvention mustnecessarily be limited to a rather narrow range in orderto efficiently produce desired cooling to within a range of 53 to 60 Fwithout imposing larger than necessary precooling and refrigerationloads on the air cooling process. i

It has been found according to the present invention that'approximately400 to 600 cubic feet of fresh air per minute per ton (CFM/ton) of netsensible in-space cooling is an adequate amount to develop conditionedair at a desirable temperature of between 53 and '60 F. The surprisingefficiency of this system can be recognized by observing thatconventional fresh air swamp coolers require about L000 CFM/ton evenwith very dry fresh air. The efficiency of the system using this airvolume range presumes 100 percent fresh (unrecirculated) air having adew point of not more than 57 F I 60 F moisture conditioned air'withsurprising efficiency and without requiring intermediate drying steps.

.having a dry bulb temperature of not less than 90 F is used.

The-warm air is first pre-cooled in a heat exchanger 62. The heatexchanger 62 may be any one of a variety of heat exchangers which willnot add moisture to the air, one suitable type being the fin-coil heatexchanger often called an extended surface heat exchanger. This type ofheat exchanger is very inexpensive to acquire and operate and is veryefficient at high temperatures.

Therefore, according to the illustrated'embodiment of the invention, thepre-cooled dry air emerging from,

the heat exchanger 62 is conducted to an air washer 64 which scrubs theair with water or, if desired, other a cooling liquid. The water usedto'scrub the pre-cooled dry air is recirculated through an externalcircuit 66 continuously. The temperature of ,the recirculating water inthe circuit 66 approaches the wet bulb temperature of the air whichenters the air washer 64. Thus,

. the entering pre-cooled air has its temperature adiabatventionalexpansion valve 78 admits refrigerant fluid into the evaporating coil76.

The use of the refrigeration circuit 70 allows the temperature of airemerging from the air washer to be reduced to the desired temperaturerange of 53 to F. Also, excess moisture in the air emerging from the airwasher 64 is condensed by the evaporating coil 76 to control themoisture content of the effluent, conditioned air. It should be observedthat unless the temperature of the air'were first adiabatically reducedin the air washer 64, a far larger and more expensive coil 76 and largerrefrigeration system 70 would be necessary to obtain the same very coldair temperature developed according to the embodiment of FIG. 1.

The system of FIG. 1 is designed to transport and condition about 400 to600 CFM/ton net sensible cool ing. Using the air having a 57 dew point,temperatures as low as 53 to 60 F may be economically and effi-.

ciently achieved. Accordingly, the effluent conditioned air has asurprisingly low temperature and controlled humidity without requiringexpensive dehumidifying (warming) and recooling steps. The FIG. 2Embodiment The embodiment of FIG. 2 differs from the embodiment of'FIG.l principally in that the evaporating coil 76 acts upon the pre-cooledair as it traverses from the heat exchanger 62 to the air washer 64(i.e., from the pre-cooling to the adiabatically cooling steps). Whenthe pre-coolecl air is further cooled, its wet bulb temperature islowered. Accordingly,'upon adiabatic-cooling in the air washer 64, itsdry bulb temperature, is further reduced to about 53 to 60 F.

4 l The moisture content of the effluent from the air washer 64 will becontrolled in proportion to the amount of cooling to which the air issubjected in advance of the adiabatic cooling in air washer 64. The drybulb and wet bulb temperatures imposed upon the air in advance of theadiabatic cooling step will determine the amount of moisture that can beadded in the adiabatic cooling step, The Embodiment of FIG. 3

The embodiment of FIG. 3 differs from the previously describedembodiments principally in that the evaporation coil 76 reduces thetemperature of recirculating water in the air washer 64. Accordingly,the temperature of the water is reduced sufficiently that both adiabaticand sensible cooling of the air results. The refrigeration system isspecifically limited to avoid exclusive refri erated cooli ngin the airwasher 64 to in- Wat efil T r Using the embodiments of FIGS. l3, coldair in the range of 53 to 60 F for air conditioning or any other desiredbeneficial use can be obtained with surprising efficiency using a 100percent fresh air system at maximum outdoor temperatures. Thus, the needfor recirculating the same air in order to reduce the costs of coolingis unnecessary. Furthermore, cold air can be obtained without usinglarge and expensive refrigeration systems. The-refrigeration system 70required for this combination of cooling steps'has been found to beapproximately one-third the size required if conventional recirculatingair refrigeration systems are employed. Accordingly, the advantages of acomplete fresh air system can be substituted for the lower quality, moreexpensive recirculating air systems.

The invention may be embodied in other specific forms without departingfrom its spirit or essential characteristics. The described embodimentsare to be considered in all respects only as illustrative and notrestrictive and the scope of the invention is, therefore, indicated bythe appended claims rather than by the foregoing description. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

What is claimed and desired to be secured by United States letterspatent is:

1; A process for controlling the temperature and moisture content of airhaving a dew pointof not more than 57 corresponding to at least F drybulb tem perature, sequentially preparing an air flow path accommodating400-600 CFM/ton net sensible cooling;

drawing fresh dry air exclusively from a fresh air source and throughthe flow path in the amounts of 400 to 600 CFM/ton net sensible cooling;pre-cooling the fresh air with a heat exchanger without altering itsmoisture content; scrubbing the air with recirculating water toadiabatically cool the air; and

refrigerating the adiabatically cooled air to further cool the air towithin a range of 53 to 60 F and coincidentally condensingexcessmoisture.

2. A process for conditioning air sequentially comprising (a) firstcooling I00 percent fresh air having a dew point of notmore than 57corresponding to at least 90 F dry bulb temperature without altering itsmoisture content; (b) second cooling the air adiabatically'byscrubbingthe dry air with recirculating water; (0) third cooling the air byrefrigeration towithin the range of 53 to 60 F with coincidentalcondensation of excess moisture, all three cooling steps being appliedvsequentially to air quantities exclusively within the range of 400 to600 CFM/ton net sensible cooling.

uent air is within the range of?" Y5 UNITED STATES PATENT OFFICECERTIFICATE OF CORRECTION Patent No. 3,812,685 Dated May 28, 1974Inventor(s) Ted R. Brown It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Column 2, line 21, "dew point" should be -wet bulb temperature.

Signed and sealed this 1st day of October 1974.

(SEAL) Attest:

McCOY M. GIBSON JR. (3. MARSHALL DANN Attesting Officer Commissioner ofPatents ORM PO-IOSO (10-69) w u.s. GOVERNMENT PRINTING OFFICE: as"O--366-33l,

1. A process for controlling the temperature and moisture content of airhaving a dew point of not more than 57* corresponding to at least 90* Fdry bulb temperature, sequentially preparing an air flow pathaccommodating 400-600 CFM/ton net sensible cooling; drawing fresh dryair exclusively from a fresh air source and through the flow path in theamounts of 400 to 600 CFM/ton net sensible cooling; pre-cooling thefresh air with a heat exchanger without altering its moisture content;scrubbing the air with recirculating water to adiabatically cool theair; and refrigerating the adiabatically cooled air to further cool theair to within a range of 53* to 60* F and coincidentally condensingexcess moisture.
 2. A process for conditioning air sequentiallycomprising (a) first cooling 100 percent fresh air having a dew point ofnot more than 57* corresponding to at least 90* F dry bulb temperaturewithout altering its moisture content; (b) second cooling the airadiabatically by scrubbing the dry air with recirculating water; (c)third cooling the air by refrigeration to within the range of 53* to 60*F with coincidental condensation of excess moisture, all three coolingsteps being applied sequentially to air quantities exclusively withinthe range of 400 to 600 CFM/ton net sensible cooling.